Laboratory of Cognitive and Computational Neuroscience, Center of Biomedical Technology, Madrid, Spain.
J Alzheimers Dis. 2010;22(1):183-93. doi: 10.3233/JAD-2010-100177.
Mild cognitive impairment (MCI) has been considered an intermediate state between healthy aging and dementia. The early damage in anatomical connectivity and progressive loss of synapses that characterize early Alzheimer's disease suggest that MCI could also be a disconnection syndrome. Here, we compare the degree of synchronization of brain signals recorded with magnetoencephalography from patients (22) with MCI with that of healthy controls (19) during a memory task. Synchronization Likelihood, an index based on the theory of nonlinear dynamical systems, was used to measure functional connectivity. During the memory task patients showed higher interhemispheric synchronization than healthy controls between left and right -anterior temporo-frontal regions (in all studied frequency bands) and in posterior regions in the γ band. On the other hand, the connectivity pattern from healthy controls indicated two clusters of higher synchronization, one among left temporal sensors and another one among central channels. Both of them were found in all frequency bands. In the γ band, controls showed higher Synchronization Likelihood values than MCI patients between central-posterior and frontal-posterior channels and a high synchronization in posterior regions. The inter-hemispheric increased synchronization values could reflect a compensatory mechanism for the lack of efficiency of the memory networks in MCI patients. Therefore, these connectivity profiles support only partially the idea of MCI as a disconnection syndrome, as patients showed increased long distance inter-hemispheric connections but a decrease in antero-posterior functional connectivity.
轻度认知障碍（MCI）被认为是健康衰老和痴呆之间的中间状态。早期阿尔茨海默病的解剖连接损伤和突触逐渐丧失表明 MCI 也可能是一种断开连接综合征。在这里，我们比较了在记忆任务期间使用脑磁图（MEG）记录的患者（22 名）和健康对照者（19 名）的脑信号同步程度。同步似然度是一种基于非线性动力系统理论的指数，用于测量功能连接。在记忆任务中，与健康对照组相比，患者在左前颞额区和右前颞额区之间（所有研究的频带）以及γ频带的后区显示出更高的半球间同步性。另一方面，健康对照组的连接模式表明存在两个更高同步性的簇，一个在左侧颞部传感器之间，另一个在中央通道之间。它们都存在于所有频带中。在γ频带中，与 MCI 患者相比，对照组在中央后和额后通道之间以及后区显示出更高的同步似然值。半球间增加的同步值可能反映了 MCI 患者记忆网络效率低下的补偿机制。因此，这些连接模式仅部分支持 MCI 作为断开连接综合征的观点，因为患者表现出远距离半球间连接增加，但前-后功能连接减少。
